Hydraulic wheel motors have been used on various automotive and non-automotive types of vehicles. In particular, hydraulically driven vehicles have achieved a fair degree of commercial success in farm vehicles.
These hydraulic wheel motors are provided with a rotary member and a stationary member having a plurality of cavities for pumping hydraulic oil which periodically varies in displacement as the stationary and the rotary member move relative to one another. Hydraulic oil from an engine driven pump is supplied to the hydraulic wheel motors for propelling the vehicle.
A vehicle that is solely driven by hydraulics has the advantage of eliminating mechanical drive train components such as a conventional transmission, clutches, and driveshaft. However, while a vehicle of this type has been used in slower moving farm or off road vehicles, various challenges exist to provide a mainstream hydraulically driven vehicle.
In particular, normal driving situations put various stresses on a hydraulic system that can lessen the driving experience. Furthermore, conventional vane-based hydraulic motors are not efficient enough to provide ideal power in an economical manner. Since vehicles with hydraulic power trains between the engine and the wheels have various advantages, such as not requiring a conventional drive train, it is desirable to make an improved vehicle that has the aforementioned advantages over a vehicle with a conventional drive train.